Cleaner forms of storing energy are in great demand. Examples of clean energy storage include rechargeable lithium (Li) ion batteries (i.e., Li-secondary batteries), in which Li+ ions moves from the negative electrode to the positive electrode during discharge. In numerous applications (e.g., portable electronics and transportation), it is advantageous to use a solid state Li ion battery which consists of all solid state materials as opposed to one that includes liquid components, (e.g., flammable liquid electrolytes), due to safety as well as energy density considerations. Solid state Li ion batteries which incorporate a Li-metal negative electrode advantageously also have significantly lower electrode volumes and correspondingly increased energy densities.
Critically important components of a solid state battery include the electrolyte, which electrically isolates the positive and negative electrodes, and, often, also a catholyte, which is intimately mixed with a positive electrode active material to improve the ionic conductivity therein. A third important component, in some Li ion batteries, is an anolyte which is laminated to, or in contact with, an anode material (i.e., negative electrode material; e.g., Li-metal). Currently available electrolyte, catholyte, and anolyte materials, however, are not stable within solid state battery operating voltage ranges or when in contact with certain cathode or anode active materials (e.g., metal fluorides).
Garnet (e.g., Li-stuffed garnet) is a class of oxides that has the potential to be suitable for use as a catholyte, electrolyte, and, or, anolyte in an all solid state battery. However, garnet materials have yet to be prepared with the proper morphology (e.g., thin film or nanostructured powder) or with sufficient conductivity and, or, particle connectivity to function sufficiently well. Certain garnet materials and processing techniques are known (e.g., U.S. Pat. Nos. 8,658,317, 8,092,941, and 7,901,658; U.S. Patent Application Publication Nos. 2013/0085055, 2011/0281175, 2014/0093785, and 2014/0170504; also Bonderer, et al. “Free-Standing Ultrathin Ceramic Foils,” Journal of the American Ceramic Society, 2010, 93(11):3624-3631; and Murugan, et al., Angew Chem. Int. Ed. 2007, 46, 7778-7781) but these materials and techniques suffer from a variety of deficiencies such as, but not limited to, insufficient conductivity or processing conditions which are incompatible with certain solid state battery components.
Accordingly, there is a need for improved methods of making and processing garnet materials, particularly with regard to the integration of garnet films and powders with cathode active material in all solid state batteries. The following disclosure provides, in part, many solutions to these as well as to other problems in the relevant field to which the instant disclosure relates.